1. Field of the Invention
The present invention relates generally to a shirred concertina of a seamless, tubular casing for foodstuffs, that is capable of being tied off at one end, and has an outer surface that can be coated or impregnated with a material containing a food additive. A concertina of the present invention is particularly adapted for use with automatic sausage-filling, portioning, and clipping machines.
2. Description of Related Art
Tubular foodstuff casings can be shirred to permit them to be filled with sausage or other edible material in a single operational step, without interruption, along a linear unit. As such, it is possible to achieve a partially continuous mode of operation. When the shirring process is completed, approximately 30 to 100 m of tubular casing form a so-called concertina, (a generally accordion-shaped shirred casing), approximately 30 to 100 cm in length, depending, among other things, on the wall thickness of the casing. Ordinarily one end of the casing, which has been shirred in sections, is then closed off. Generally, clips made of plastic or metal have proven effective for closing off one end of the casing. The same result may be achieved with a simple tying-off.
Methods for turning unshirred tubular casings are known in the art. However, they require expensive equipment (see for example, DE 11 98 988 and DE 14 79 836), and are generally not necessary in producing or processing a concertina of the present invention. One process for simultaneously filling and turning of a tubular food casing involves coating the outer surface with a barrier layer to prevent oxygen and water vapor from permeating the casing (specifically a PVDC layer), as described for example in EP-A 004 620.
Also known-in-the-art are processes for coating or impregnating the outer or inner surfaces of tubular food casings, especially sausage casings, with liquid smoke. Application of such materials to the outer surface of casings is generally easier in terms of process engineering. However, components of the liquid smoke should generally pass through the casing in order to give a sausage product a typical color, aroma, and flavor of smoke. Cellulose casings impregnated with liquid smoke on their outer surface are widely known. Frequently, casings that do not include cellulose in a sufficient amount are not permeable enough to be treated with liquid smoke or the like. This is true of single-layer synthetic casings, and certainly of multilayer synthetic casings. In any case, such casings can be treated with liquid smoke on their inner surface. However, inner surface treatment may result in the liquid smoke not adhering sufficiently to the surface, and instead collecting forming droplets.
One approach to solving this problem is described, for example, in DE-A 196 08 001. The idea therein is to apply liquid smoke to a thin film that is cut to size and is then shaped to form a tube, with the side that is coated with the liquid smoke being turned inwardly. The tube is then permanently sealed via a heat-sealing process, leaving a longitudinal seam. The application of the liquid smoke and the production of the tube are completed just before the tube is filled with the sausage product. The sealed tube is not shirred. However, in the area around the seam, the liquid smoke components are not evenly applied. When the casing is peeled off, this unevenness becomes obvious as evidenced by spotting or uneven coloration on the surface of the sausage. Furthermore, because of the seam, the mechanical resistance of the casing is not great enough. Bacteria are able to work their way into the sausage product through defective points along the seam. In addition, because the sealed ends overlap, or are covered with a sealing strip, the casing thickness is not uniform throughout since the casing is thicker along the seam. A concertina produced from this type of casing would be uneven and thus difficult to process.
EP-A 986 957 describes seamless food casings based on synthetic materials provided on their inner surface with a layer containing a component that transfers a particular aroma, flavor, or color to the sausage product, emulsified in a binding agent. Binding agents considered particularly well-suited include alginates, methyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose, hydroxypropyl starches, chitosan, albumin, pectin, carrageenan, casein, and soy or wheat protein. Polysaccharides that are esterified with aliphatic dicarboxylic acid anhydrides or etherified with acrolein, epichlorohydrin, ethylene glycol, ethylene oxide, or similar compounds are also listed as being well suited. As aroma, flavoring, and/or coloring agents, spices (especially pepper), chicken flavoring, lemon oil, orange oil, honey, sorrel, cinnamon, and sugar (especially brown sugar) are mentioned. The food casings coated on their inner surface in this manner are intended for use with packaging cooked meat products. For example, are coated pouches for packaging cooked chicken breast. The pouches are sealed in a heat-sealing process. When heated a second time—for example in a microwave—the flavor, color, and aroma are transferred to the surface of the chicken breast.
In EP-A 408 164, a packaging material for foodstuffs is described. It comprises a waterproof carrier layer and a contact layer, to which herbs, spices, roe, fish paste, cheese, vegetable extracts, or similar foodstuffs, in the form of powder, granules, or chips, adhere. The contact layer is composed substantially of polysaccharides, such as starches, dextrin, acacia gum, sodium carboxymethyl cellulose, gelatins, or similar substances suitable for use in foodstuffs. The packaging material can be shaped to form a tube that is closed with a sealed seam. Such tubular food casings are used especially in the production of cooked ham. During the cooking process the spices or other food additives are transferred from the inner surface of the casing to the cooked ham.
In WO 97/36798, a heat-shrinking, flat, or tubular food casing is described, the inner surface of which comprises a layer of a copolymer and a food additive. The copolymer contains segments that are virtually insoluble in water, and hygroscopic. Pigments, aromas, flavorings, antioxidants, antimicrobials, enzymes, aroma-binding agents, and liquid smoke are listed as suitable food additives. These are at least partially transferred to the foodstuff contained in the casing.
A heat-shrinking foil is described in WO 98/31731. Where the inner coating thereof comprises a mixture of (i) an additive, composed of an aroma ingredient, a flavoring, a dye, an antimicrobial agent, a chelating agent, and/or an aroma-absorbing agent; (ii) a polysaccharide or protein as a binding agent; and (iii) a cross-linking agent, containing at least two carbonyl groups. The additive may be caramel, liquid smoke, paprika, benzoic acid, EDTA, tocopherol, sorbitol, or polyphosphate. Tubular films coated on the inner surface are then produced from the corresponding sheet films. The coating process is accomplished using a roller. During this process, the edges are not coated. The sheet film is then formed into a tube, and the overlapping edges of the film are securely sealed in a heat-sealing process. The casing obtained in this manner is shirred, and closed at one end using a clip. The casing is then filled with a meat product and cooked. This causes the additive present in the inner coating of the casing to be transferred to the meat product. As explained above, tubular films having a sealed seam cannot be shirred into an evenly shaped concertina. Furthermore, a process described in WO 98/31731, wherein a seamless tubular film is produced, cut open, coated, and again sealed to form a tube, such a process is very costly and susceptible to problems. In addition, the food additives contained in the inner coating of the film are not always evenly transferred in the area around the sealed seam, because the edges of the film are left uncoated in order to prevent interference with the heat sealing process. Therefore, in many cases, there is an uneven distribution of inner coating (or even complete lack of coating) present in the areas around the seam. This becomes particularly problematic when highly pigmented additives, such as liquid smoke, are to be transferred.